Hybrid space frame for motor vehicle

ABSTRACT

A space frame for an motor vehicle having hydroformed upper and lower longitudinal members and hydroformed cross-members. Each upper longitudinal member is connected to a corresponding lower longitudinal member in the front and at the rear of the frame by members formed of stamped sheet metal. The stamped components can form part of the front and rear wheel wells. The use of stamped members to connect hydroformed members can permit the use of hydroformed members in motor vehicles with minimum amounts of space for frame members.

[0001] The present application claims priority to U.S. ProvisionalApplication Serial No. 60/272,468, filed Mar. 2, 2001, the entirety ofwhich is hereby incorporated into the present application by reference.

FIELD OF THE INVENTION

[0002] The present invention is generally related to motor vehicleframes and more particularly to motor vehicle space frames constructedusing hydroformed members.

BACKGROUND OF THE INVENTION

[0003] Tubular hydroforming is increasingly used in vehicle frameconstruction because tubular hydroforming offers automobilemanufacturers many commercial advantages. The use of tubularhydroforming enables manufacturers to better control frame stiffness,dimensional stability, fatigue in life, and vehicle crashworthiness overprior vehicle designs while reducing frame mass and cost. Hydroformingis a metal-forming process in which high-pressure fluid is used tooutwardly expand a tubular metal blank into conformity with the surfacesof a die cavity of a die assembly to form an irregularly shaped tubularpart. Hydroformed members can be provided with a wide range ofgeometries in comparison with other methods of forming parts. Eachhydroformed frame member can be constructed to have a cross-sectionalconfiguration that varies continuously along its length, to theconfiguration desired and each frame member can be constructed to curveor “bend” along its length to define different frame parts such as frameside rails and frame pillars.

[0004] Depending on specific circumstances, certain “sharp” bends maynot be advantageous or possible due to particular space constraints forcertain motor vehicle designs. Space frames are cage-like structures onwhich other vehicle components, including the engine, drive train,suspension and the hang-on vehicle body parts, can be mounted. Tubularhydroformed space frames may be used in the construction of relativelylarge vehicles such as sports utility vehicles and larger sedans andtrucks. In relatively larger frame vehicles, angular limitations on theconstruction on tubular hydroformed members generally pose few problems.However, the limited space available in some motor vehicles such ascompact or other smaller frame cars can limit the use of hydroformedspace frames therein. This is especially true when the motor vehicle hasset interior and exterior configurations and the frame must be fitbetween the two.

[0005] There is a need for a vehicle space frame that can provide thebenefits of tubular hydroformed construction for smaller frame vehicleswith limited frame space.

SUMMARY OF THE INVENTION

[0006] To meet the needs expressed above, the present invention providesspace frame for a motor vehicle that includes a pair of tubular,hydroformed longitudinally extending lower side rail members and a pairof tubular, hydroformed upper longitudinal members. Each of the upperlongitudinal members includes a rear pillar-forming portion and arail-forming portion, each of the pillar-forming portions being coupledto an end of a respective one of the lower side rail members andextending upwardly therefrom to define a rearward-most pillar of themotor vehicle and each of the rail-forming portions extending forwardlyfrom the pillar-forming portion to define a roof support rail of themotor vehicle. The space frame further includes a pair of forward-mostpillar assemblies, each of the pair of forward-most pillar assembliesbeing coupled to a respective one of the pair of lower side rail membersand extending upwardly therefrom and being coupling with a respectiveone of the upper longitudinal members, and each of the forward-mostpillar assemblies being formed from stamped sheet metal. A laterallyextending connecting structure is mounted between the pair of lower siderail members, the connecting structure being constructed and arranged tohold the pair of lower side rail members in laterally spaced relation toone another.

[0007] The invention further provides space frame for a motor vehiclecomprising a pair of tubular, hydroformed longitudinally extending lowerside rail members and a pair of tubular hydroformed upper longitudinalmembers. Each of the upper longitudinal members includes a rearpillar-forming portion and a rail-forming portion, each pillar-formingportion being coupled to an end of a respective one of the lower siderail members and extending upwardly therefrom to define a rearward-mostpillar of the motor vehicle and each of the rail-forming portionsextending forwardly from the rear pillar-forming portion to define aroof support rail of the motor vehicle. The space frame further includespair of pillar support structures, each pillar support structure beingof stamped sheet metal construction and each being connected to arespective lower side rail member at the location to support aforward-most pillar structure. The space frame also includes a pair offorward-most pillar structures, each pillar structure being coupled at alower end thereof to an associated pillar support structure and beingcoupled at an upper end thereof to an associated upper longitudinalmember. A laterally extending connecting structure is mounted betweenthe pair of lower side rail members, the connecting structure beingconstructed and arranged to hold the pair of lower side rail members inlaterally spaced relation to one another.

[0008] Other objects, features, and advantages of the present inventionwill become apparent from the following detailed description, theaccompanying drawings, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWING

[0009] FIGS. 1-4 show various stages of assembly of an exemplary vehicleillustrating an embodiment of the invention, FIGS. 1-4 particularlyshowing the assembly of a space frame of the vehicle and showing variousbody panels mounted to the space frame;

[0010]FIG. 1 illustrates an embodiment of the present inventionincluding a lower frame assembly of the space frame in isolation;

[0011]FIG. 2 shows the lower frame assembly of FIG. 1 with various bodypanels secured thereto;

[0012]FIG. 3 shows the frame assembly of FIG. 2 with an upper frameassembly mounted thereto;

[0013]FIG. 4 shows the space frame of FIG. 3 with additional body panelsstructures mounted thereto;

[0014]FIG. 5 is an isolated view of a hydroformed portion of theassembled space frame of FIGS. 1-4 with stamped sheet metal portionsthereof removed and not shown;

[0015]FIG. 6 is an exploded view of a forward-most pillar assembly ofthe space frame of FIGS. 1-4;

[0016]FIG. 7 is a cross sectional view taken through the 7-7 asindicated in FIG. 4;

[0017]FIG. 8 is a cross sectional view taken through the 8-8 asindicated in FIG. 4;

[0018]FIG. 9 is an exploded view of a pillar support structure of thespace frame of FIGS. 1-4;

[0019]FIG. 10 is an assembled view of a pillar support structure on ofthe space frames of FIG. 1-4;

[0020]FIG. 11 is an exploded view of a portion of the space frame in thevicinity of a joint formed between a B pillar of the space frame and aside rail member of the space frame of FIGS. 1-4;

[0021]FIG. 12 is a cross sectional view taken through 12-12 as indicatedin FIG. 4;

[0022]FIG. 13 is a cross sectional view taken through 13-13 as indicatedin FIG. 4, and additionally illustrating a door and door seal;

[0023]FIG. 14 is a cross sectional view taken through 14-14 as indicatedin FIG. 4;

[0024]FIG. 15 is a cross sectional view taken through 15-15 as indicatedin FIG. 4;

[0025]FIG. 16 is a cross sectional view taken through 16-16 as indicatedin FIG. 4;

[0026]FIG. 17 is a cross sectional view taken through 17-17 as indicatedin FIG. 4 and additionally illustrating a door and door hinge assembly;

[0027]FIG. 18 is a cross sectional view taken through 18-18 as indicatedin FIG. 4 and additionally illustrating a door seal attached to theC-pillar;

[0028]FIG. 19 is a cross sectional view taken through 19-19 as indicatedin FIG. 4 and additionally illustrating a partial, cross-sectional viewof the vehicle lift gate and its associated pivot mechanism;

[0029]FIG. 20 is an exploded view of a portion of the space frame ofFIGS. 1-4 showing an upper longitudinal member of the space frame and aroof rail outer structure mounted thereon in fragmentary view andshowing various components that are mounted to the space frame in thevicinity of a transition between a roof rail portion of the upperlongitudinal member and a pillar forming portion of the upperlongitudinal member in fragmentary view;

[0030]FIG. 21 is a cross sectional view taken through 21-21 as indicatedin FIG. 4;

[0031]FIG. 22 is an exploded view of portions of the space frame ofFIGS. 1-4 and components mounted thereto in the vicinity of a jointbetween the roof rail portion of the upper longitudinal member and across member of the space frame;

[0032]FIG. 23 is a cross sectional view taken through 23-23 as indicatedin FIG. 4 and illustrating a portion of a vehicle door;

[0033]FIG. 24 is a cross sectional view taken through 24-24 as indicatedin FIG. 4;

[0034]FIG. 25 is a cross sectional view taken through 25-25 as indicatedin FIG. 4; and

[0035]FIG. 26 is a schematic view of a tubular hydroforming die assemblyshowing a blank mounted therein for forming certain members found in theframe of FIGS. 1-4.

DETAILED DESCRIPTION OF THE INVENTION

[0036] FIGS. 1-4 show various stages of assembly of an illustratedembodiment of the invention in the form of a motor vehicle space frame.The space frame 10 is generally illustrated with a plurality of bodypanels mounted thereto. Vehicle space frames for any size vehicle may beconstructed utilizing the principles of vehicle construction taught bythe illustrated embodiment. The space frame 10 is particularlywell-suited for the construction of a compact, sub-compact, or smallercommercial motor vehicles (generally referred to as “smaller framevehicles” in the present application). As will become apparent, thespace frame 10 utilizes a significant amount of tubular hydroformedconstruction to allow the vehicle manufacturer to have the advantage ofthe benefits offered by tubular hydroformed technology (such asreduction of frame weight without compromising vehicle crashworthiness,reduction of the total number of frame parts and of the number of weldsrequired for frame assembly, reduction in the amount of waste generated,and so on) and utilizes non-hydroforming construction, such as stamping,to optimize the amount of tubular hydroformed construction that can beincorporated into the smaller frame vehicle. These advantages willbecome apparent as the construction on the space frame 10 is consideredin detail. Hydroformed space frames are generally known as in U.S. Pat.No. 6,092,865 to Jaekel et al., which is incorporated herein byreference, in its entirety.

[0037]FIG. 1 shows a lower frame assembly 12 of the space frame 10 inisolation. The lower frame assembly 12 includes a pair of longitudinallyextending, laterally spaced lower side rail members 14, 16 of tubularhydroformed construction. Because the lower side rail members 14, 16 areof mirror image construction, only rail member 14 will be discussed indetail, but the discussion applies equally to rail member 16.Corresponding portions of rail members 14 and 16 are labeled withidentical reference numbers in the present application to facilitatediscussion of the invention, but it is understood that thesecorresponding portions are of mirror image construction.

[0038] Rail member 14 is of three-piece construction and includes atubular hydroformed forward rail portion 18, a central rail portion 20and a rearward portion 22. These portions 18, 20, 22 are telescopicallyinterengaged and welded together at joints 24 and 26, respectively.

[0039] The forward portion 18 of rail member 14 includes a forward“crash tip” section 28 and a relatively straight, longitudinallyextending rearward section 30. The central portion 20 of rail member 14includes a relatively straight, longitudinally extending forward section32, and generally outwardly angled (in the longitudinal front to rearvehicle direction) intermediate section 34 and a longitudinallyextending, relatively straight rearward section 36. The rearward railportion 22 includes a longitudinally extending, relatively straightforward section 38, an inwardly (in the longitudinal front to rearvehicle direction) angled intermediate section 40, and a longitudinallyextending, relatively straight rearward section 42.

[0040] A bumper assembly 45, which can be of stamped sheet metalconstruction, is mounted on the forwardmost ends of the rail members 14,16. The crash tip section 28 of rail member 14 is constructed andarranged to absorb impact in the event of a vehicle head on collision. Apillar support structure 44, 46, which can be of stamped sheet metalconstruction, is connected to the exterior surface of a rail member 14or 16, respectively, by welding or other suitable method, generally inthe area of transition between sections 34 and 36 thereof Because thepillar support structures 44, 46 are of mirror image construction, onlystructure 44 will be considered in detail, but the discussion appliesequally to structure 46. Corresponding portions of the structures 44, 46are labeled with identical reference numerals even though they are ofmirror image construction. The pillar support structure 44 includes aninner support element 48 and an outer support element 50.

[0041] The forward sections 30, 32, 34 of the rail member 14 and theinner support element 48 of the support structure 44 generally define afront wheel well 52. The outer support element 50 on the supportstructure 44 and the straight longitudinally extending sections 36 and38 of the rail member 14 generally define a rocker panel portion 54 ofthe lower frame assembly 12. The rearward sections 40 and 42 of the railmember 14 generally define a rear wheel well 56. The forward sections30, 32, 34 of the rail members 14, 16 generally define an enginecompartment area 58 of the lower frame assembly 12. Similarly, sections36 and 38 of the rail members 14, 16 generally define a passengercompartment area 60 of the assembly 12 and sections 40 and 42 of therail members 14, 16 generally define a rear cargo area 62 of the frameassembly 12.

[0042] A plurality of laterally extending connecting structuresgenerally designated 64 are connected between the lower side railmembers 14, 16 and are constructed and arranged to hold the same inlaterally spaced fixed relation to one another. The connecting structure64 includes a pair of first and second central connecting members 66, 68(which have closed cross sections and which may be, for example, ofhydroformed or roll formed construction) and third central connectingstructure 70. The third connecting structure 70 has an open, essentiallyC-shaped cross section and may be of the stamped sheet metalconstruction. Opposite ends of the connecting members 66, 68 are securedto the rails 14, 16 at joints 72, 74, respectively. Joints 72 and 74 areessentially identical in construction and are formed by cutting holes inopposing walls of each of the rail members 14, 16 and securing oppositeends of the connecting members 66, 68 in respective pairs of openings bywelding. The connecting member 70 is connected between the rail members14, 16 by welding opposite ends of the member 70 to exterior surfaceportions of the respective rail members 14, 16.

[0043] A pair of the inwardly spaced, longitudinally extending railmembers 76, 78 are connected between the angled sections 34, 40,respective, of the rail members 14, 16. Because the inner rail members76, 78 are of mirror image construction only rail member 76 will bediscussed in detail but the discussion applies equally to rail member78. The rail member 76 is preferably of stamped, open cross sectionsheet metal construction and has an open, essentially C-shaped crosssection. Preferably the rail member 76 is secured to the lower frameassembly 12 by welding opposite ends of the member 76 to inwardly facingexterior wall surfaces on sections 34 and 40, respectively, of the railmember 14. The laterally extending members 66, 68, 70 are secured bywelding or by other suitable method in notches 80, 82, 84, respectively,formed in the longitudinally extending rail member 76.

[0044] The cross structure 64 further includes a pair of rearwardconnecting structures 86, 88. Each rearward connecting structure 86, 88preferably has an open, essentially C-shaped cross section and is asheet metal structure that has been shaped by stamping. The connectingstructure 86 is secured to the frame assembly 12 by securing oppositeends thereof to inwardly facing exterior surfaces of the inner railmembers 76, 78 by welding or other suitable method. The connectingstructure 88 is secured to the frame assembly 12 by welding oppositeends thereof to inwardly facing exterior surfaces of opposing sections42 of the rail members 14, 16. A rearward most connecting member 90 issecured between the rail members 14, 16 at joints 92. Preferably theconnecting member 90 is of tubular construction (i.e., has a closecross-section) and may be formed by hydroforming, by roll forming or anyother appropriate method. Joints 92 are similar in construction tojoints 72 (see FIG. 15 for a cross sectional view of joint 92).

[0045] As shown in FIGS. 2-4, a plurality of the vehicle components,each can be formed from non-hydroforming methods such as of stamped,sheet metal construction, are secured to the lower frame assembly 12.These components include floor pan structures, a pair of forward-mostpillar assemblies 94, 96 and a pair of rear pillar support assemblies98, 99. More specifically, the central floor pan structure 100 issecured to intermediate portions of the rail members 14, 16 and toportions of the cross members 66, 68, 70 and 86, by welding or otherappropriate method. A rear floor pan 102 is secured to rearward portionsof the rail members 14, 16 and to cross members 88 and 90 by welding orother appropriate method. The floor pans 100, 102 can be of stampedsheet metal construction and provide the floor structure for thepassenger compartment 60 and the cargo compartment 62, respectively.

[0046] A lower portion of a dash panel 104, which can be of stampedsheet metal construction, is welded to the lower frame assembly 12 atthe forward end of the passenger compartment area 60. The dash panel 104supports various vehicle structures in the assembled vehicle includingan instrument panel (not shown), a lower portion of a vehicle windshield(not shown) and various vehicle controls and also functions as afirewall between the passenger and engine compartments.

[0047] The construction of the forward-most pillar assembly 94 and themanner in which the pillar assembly 94, the side rail member 14, thepillar support structure 44 and the dash panel 104 are interconnectedcan be appreciated from FIGS. 6-8. The pillar assemblies 94, 96 part ofmirror image construction. Only assembly 94 will be discussed in detail,but the discussion applies equally to the assembly 96.

[0048] The forward-most pillar assembly 94 is a multi-piece assembly ofstamped sheet metal structures that provides the space frame 10 with aforward-most or A pillar and provides support and attachment structurefor a hydroformed roof rail 106 (shown in fragmentary view, for example,in FIG. 6) of the tubular hydroformed upper frame assembly describedbelow. The construction of the pillar assembly 94 is best understoodfrom the exploded view of FIG. 6. FIG. 6 shows in fragmentary view thecentral portion 20 of the rail member 14 in exploded relation with therearward portion 20 to thereof. The telescopic nature of theinter-engagement of joint 26 can be appreciated from the exploded viewof FIG. 6. An outer edge 108 of a lower, essentially horizontallyextending wall portion 110 of the inner support element 48 of the pillarsupport structure 44 is welded to a downwardly facing surface of therail member 14 generally in the vicinity of transition between a rockerpanel-forming section 36 of the rail member 14 and the angled section 34of the rail member 14. An essentially vertical wall portion 112 of theinner support element 48 of the pillar support structure 44 defines therearward extent of the front wheel well 52. The outer support element 50of the pillar support structure 44 is secured to the inner supportelement 48 preferably by welding to form a box-like support structuregenerally between the rocker panel portion of the side rail member 14(i.e., sections 36 and 38 thereof) and the front wheel well to supportthe forward-most pillar assembly 98. The outer element 50 provides aforward portion of the rocker panel 54. The support structure 44provides a support for inner and outer pillar members 114, 116,respectively, of the pillar assembly 98. The inner and outer pillarmembers 114, 116 provide a pillar structure for the space frame 10 thedefines the A pillar. The inner and outer pillar members 114, 116 thusform the vehicle A pillar and provide attachment structure for thetubular hydroformed roof rail 106 to the A pillar.

[0049] The inner and outer pillar members 114, 116 can be stamped sheetmetal structures that are preferably secured to one another and to thesurrounding stamped sheet metal and tubular hydroformed components bywelding, although any appropriate method can be used to secure thesestructures to one another.

[0050] A lower portion 118 of the inner pillar 114 is welded within thebox-like pillar support structure 44 (see the cross section of FIG. 8).An intermediate portion 120 of the inner pillar member 114 is secured toan edge of the dash panel 104. A reinforcement structure 121, can be ofstamped sheet metal construction and may be welded in reinforcingrelation between the dash panel 104 and the inner pillar member 114. Anupper portion 122 of the inner pillar member 114 is secured to an upperedge of the dash panel 104 and to upper and lower plenum structures 124,126, respectively.

[0051] A lower portion 128 of the outer pillar member 116 is secured tothe exterior of the outer support element 50 of the pillar supportstructure 44 and to a portion of the side rail member 14 and an upperportion 130 of the outer pillar member 116 is secured to the innerpillar member 114 in the assembled vehicle space frame 10. The roof railportion 106 of a tubular hydroformed member is generally securedtherebetween. FIG. 2 shows the pillar support member 44, the innerpillar member 114, the dash panel 104 and the upper and lower plenumstructures 124, 126 mounted on the lower frame assembly 12.

[0052]FIG. 2 also shows the pillar support assemblies 98, 99 mounted onthe lower frame assembly 12. The pillar support assemblies 98, 99 are ofsimilar construction and may be of mirror image construction. Thestructure of pillar support assembly 98 is considered in detail and theconstruction of pillar support assembly 99 is briefly discussed and canbe understood from the discussion of assembly 98.

[0053] The pillar support assembly 98 is shown in exploded view in FIG.9. FIG. 9 shows the portion of the rail member 14 that defines the rearwheel well 56 in fragmentary view. The pillar support assembly 98includes a rear wheel house structure 132, a rear quarter panel innerstructure 134, an inner pillar support structure 136, an outer pillarsupport structure 138 and an outer rear quarter panel structure 140.

[0054] A lower edge 142 of the rear wheel house structure 132 is weldedto sections 40 and 42 of the rail member 14. A lower portion of the rearwheel house structure 132 defines a portion of the rear wheel well 56.The rear quarter panel inner structure 134 is secured to the wheel housestructure 132 and to a rearward portion of the rail member 14 (see, forexample, FIG. 2), preferably by welding. The inner pillar supportstructure 136 is secured to the rail member 14, the rear wheel housestructure 132 and to the rear quarter panel inner structure 134,preferably by welding. As shown, for example, in FIG. 4, the innerpillar support structure 136 includes support structure 144, which canbe shaped by stamping, to receive a lower end portion of the tubularhydroformed member 146 (shown in fragmentary view in FIG. 9) thatprovides a C pillar for the space frame 10. The outer pillar supportstructure 138 is secured to a portion of the rail member 14 and to aportion of the inner pillar support structure 136, preferably bywelding. The outer pillar support structure 138 includes stampedstructure 148 that is constructed and arrange to support the tubularhydroformed C pillar 146. Structures 134, 136, and 138 can all be madeof non-hydroforming methods, such as stamped sheet metal construction.

[0055] Optionally, a pair of weld openings 150 may be provided in theouter pillar support structure 138 to help secure the C pillar 146 tothe support structure 138. The outer rear quarter panel structure 140 iswelded to portions of the inner and outer pillar support structures 136,138, to the rear quarter panel inner structure 134, to the C pillar 146and to the adjacent D pillar 152 (see, for example, FIG. 4). It can alsobe appreciated from FIG. 4 that the rear quarter panel inner and outerstructures 134, 140 are each provided with openings 154, 156 toaccommodate vehicle tail lights.

[0056] The partially assembled pillar support assembly 99 is shown inenlarged view in FIG. 10. The pillar support assembly 99 includes a rearwheel house structure 158, a rear quarter panel inner structure 160, aninner pillar support structure 162 and an outer pillar support structure164. As shown in FIG. 10, the inner and outer pillar support structures162, 164 cooperate to receive and support a lower portion of a C pillar146 of the space frame 10. A portion of the rear quarter panel innerstructure 160 is connected to the rear pillar 152, to the inner pillarsupport structure 162 and to the C pillar 146 which helps hold the Cpillar 146 rigidly in place.

[0057] It can be appreciated from a comparison of FIGS. 2-4 that thespace frame 10 may be constructed by mounting the floor pans 100, 102,the dash panel 104, the pillar support structures 44, 46 the innerpillar members 114, the upper and lower plenum structures 124, 126, therear wheel house structures 132, 158, the rear quarter panel innerstructures 134, 160, the inner pillar support structures 136, 162 andthe outer pillar support structures 138, 164 to the lower frame assembly12 (as shown in FIG. 2).

[0058] At this point in the construction, a tubular hydroformed upperframe assembly generally designated 170 may be mounted on the vehicleframe. The upper frame assembly 170 includes a pair of tubularhydroformed upper longitudinal members 174, 176, a first tubularhydroformed U-shaped member 178 and a second tubular hydroformedU-shaped member 180.

[0059] The upper longitudinal members 174, 176 are of mirror imageconstruction so only upper longitudinal member 174 will be discussed indetail, but the discussion applies equally to member 176. Each of thelongitudinal members 174 includes a D pillar forming portion 152 and aroof rail forming portion 106. The pillar forming portion 152 of theupper longitudinal member 174 is connected at a free end to the siderail member 14 at joint 186 and extends upwardly therefrom to define therearward most or D pillar of the space frame 10. The rail formingportion 106 of the upper longitudinal member 174 extends forwardly fromthe pillar forming portion 152 thereof to define the roof rail of thespace frame 10. The upper longitudinal member 174 is preferablyhydroformed from a single tubular blank that includes a butt weld 188.It is preferred to construct the upper longitudinal member 174 in onehydroforming operating to minimize stacked tolerances in thelongitudinal vehicle direction.

[0060] The first and second U-shaped members 178, 180 can both be ofone-piece, tubular hydroformed construction. Members 178 and 180 eachinclude cross portions 190, 192, respectively, and a pair of legs 194,146, respectively, that extends integrally from junctures 198, 200,respectively, at opposite ends of the respective cross portions 190,192.

[0061] The free end of each leg 194 of the first U-shaped member 190 issecured within an upwardly facing opening 202 formed in the respectiverail members 14, 16 to form joints 204. The roof rail 106 is welded insurface-to-surface relation to the cross member 190 at the juncture 198thereof to form a joint 206. The legs 194 of the first U-shaped crossmember 190 define a pair of B pillars of the space frame 10.

[0062] Similarly, the roof rail 106 is welded in overlyingsurface-to-surface relation to the juncture of the second cross member192 to form joint 208 and the free ends of the legs 146 of the secondcross member 192 are supported by and are welded within the structures144 and 148 (see FIG. 9) of the inner and outer pillar supportstructures 136, 138, respectively.

[0063] As can be appreciated from a comparison of FIGS. 3 and 4, theouter pillar member 116 may be welded to the pillar assembly 94 afterthe tubular hydroformed upper frame assembly 170 is assembled to thespace frame. A stamped outer support 210 (see FIG. 4) is secured to thepillar assembly 98 and extends generally forwardly therefrom. The outersupport 210 includes an inner portion 211 that is secured to the innerpillar member 114 and an outer portion 215 that is secured to the outerpillar member 116. The outer support 210 may be of stamped sheet metalconstruction and may be secured to the pillar assembly 98 by welding.The outer support 210 can be used to mount the vehicle fender and otherbody structures.

[0064] A roof panel 212, the outer rear quarter panel structures 140 anda plurality of door seal interface structures, generally designated 214,are mounted on the vehicle frame as shown, for example, in FIG. 4. Aroof panel outer structure 216, which can be of stamped sheet metalconstruction, is mounted on each side of the vehicle along the roof rail106 thereof and then downwardly along an upper portion of the D pillar152 to the outer quarter panel structure 140.

[0065]FIG. 7 shows that the inner and outer pillar members 114, 116 arewelded together along seams 215, 217 and are shaped to provide the Apillar with a closed cross section. FIG. 8 is a cross sectional viewshowing the manner in which the inner and outer pillar members 114, 116,the inner and outer support elements 48, 50 and the dash panel 104 aresecured together. Specifically, the outer pillar member 116, the outersupport element 50 and the inner support element 48 are welded togetheralong seam 219. The outer support element 50, the inner pillar member114 and the dash panel 104 are welded together along seam 221. FIG. 14shows that the outer pillar member 116 and the floor pan 100 are weldedtogether along seam 223. The outer pillar member 116 and the floor pan100 may also be welded to the rail member 14 by single sided spot welds(shown schematically) as at 225.

[0066]FIG. 11 shows an exploded view of joint 204 and of two of the doorseal interface structures 214. The opening 202 for the C pillar and aweld opening 218 may be laser cut in the side rail member 14. FIG. 12shows the assembled joint 204 in cross-sectional view. The pillar, theside rail member 14, the door seal interface structure 214 and the floorpan 100 may be secured together by a series of welds, such as MIG welds,(shown schematically) as at 220 and a series of welds, such as singleside spot welds (shown schematically) as at 222. A door seal 224 (seeFIG. 13) is mounted on the transition structure 214 in the assembled thevehicle and is positioned to engage a vehicle door 226 when the door 226is in its closed position to seal the door.

[0067]FIG. 15 shows construction of the space frame 10 the area of joint92 and 186. Joint 92 is formed by inserting the tubular connectingmember 90 through openings 228, 230 formed in opposite sides of the railmember 14 and welding the members 90, 14 together. Joint 186 is formedby cutting and removing several wall portions at a free end of thepillar portion 152 of the upper longitudinal member 174, placing thepillar portion 152 into contact with the exterior surface of the railmember 14 and welding the structures together. A rear pillar sealtransition structure 232 is welded between a lower end of the pillarportion 152 of the upper longitudinal member 174 and an upper member 234mounted on an upper surface of the rear cross member 90. The transitionstructure 232 forms a rounded corner of the rear opening 235 into thecargo compartment of the vehicle space frame 10. The structure 232 andthe member 234 are preferably each metal structures that have beenshaped by stamping and welded to the space frame 10.

[0068]FIG. 16 is a cross-sectional view showing the manner in which therear wheel house structure 132 and the floor pan 102 in the cargocompartment are mounted to the rail member 14 and to each other. Thewheel house structure 132 includes a downwardly extending flange 236that is secured by welding to the rail member 14 as, for example, by aseries of single sided spot welds (not shown). The cargo floor pan 102is welded to an upper surface of the rail member 14 and to an upper thefacing surface of the wheel house structure 132.

[0069]FIG. 17 shows a cross-sectional view of the B pillar. The B pillarhas a tubular hydroformed construction. Outwardly facing surfaces 240and 242 define seal engaging planes for a door seal (not shown in FIG.17). An internally threaded hinge attachment sleeve 244 is inserted intothe B pillar to receive a hinge bolt 246 to attach hinge 248 for avehicle door 249. The C pillar is shown in cross-section in FIG. 18. TheC pillar has a tubular hydroformed construction and defines a outwardlyfacing seal plane 250 for door seal 252.

[0070]FIG. 19 shows a cross-sectional view through the D pillar andshows a cross-sectional view of the roof panel outer 216. The roof panelouter 216 is attached to an upper prop rod attachment bracket 256another along seam 258. The roof panel outer 216 is welded to the Dpillar at seam 260 and the attachment bracket 256 is welded to the Dpillar at 262. The bracket 256 serves as a pivotal point of attachmentfor a gas stroke assembly 264 (shown schematically) than is mounted to avehicle liftgate 266 (shown in fragmentary view in FIG. 19).

[0071]FIG. 20 shows the details of the construction of the space frame10 in the vicinity of the transition between the pillar forming portion152 and the roof rail forming portion 106 of the upper longitudinalmember 176. The space frame 10 includes the roof panel 212, a liftgatehinge reinforcement structure 268, a D pillar header 270, and a roofrail to header bracket 272. FIG. 20 also shows the manner in which theroof panel outer 216 (also called the class “A” roof rail) is mounted tothe upper longitudinal member 174. FIG. 21 shows the details of themanner in which the D pillar header 270 is secured to the roof panel212. The header 270 is welded to the roof panel 212 along seam 271.

[0072]FIG. 22 shows an exploded view of the structure of the space frame10 in the vicinity of the joint 206 between the roof rail portion 106 ofthe upper longitudinal member 174 and the first cross member 190. FIG.22 shows the roof panel 212, the roof rail portion 106 of the upperlongitudinal member 174, the cross member 190, a door seal transitionstructure 214 and the roof rail outer 216. FIG. 23 shows the manner inwhich these structures are related in the assembled space frame 10.Specifically, the roof rail portion 106 is welded in surface-to-surfacerelation to the juncture 198 of the cross member 190. The door sealtransition structure 214 is welded to the roof rail portion 106 of theupper longitudinal member 174 and to a portion of the cross member 190.The roof rail outer 216 is welded to the transition structure 214 at 276and to the roof rail portion at 278. The roof panel 212 is welded to theroof rail outer 216 at 278. A vehicle door 279 is shown in fragmentaryview.

[0073]FIG. 24 is a cross sectional view through the roof rail portion106 of the upper longitudinal member 174 showing a windshield headerattachment structure 280 and the roof rail outer 216 welded to the roofrail portion 106 of the upper longitudinal member 174.

[0074]FIG. 25 shows in cross-sectional view the structure of the bumperassembly 45 and the manner in which the same is mounted to the railmember 14. Specifically, the bumper assembly 45 includes an arcuateinner bumper element 284 and an outer bumper element 286 welded thereto.A bumper attachment structure 290 is welded to the inner bumper element284. A pair of bumped connecting members 292, 294 are welded between theattachment structure 290 and the forwardmost end of the rail member 14to attach the bumper assembly 45 to the side rail member 14. Anattachment bracket 296 is secured between an outer portion of the bumperelement 284 and a side portion of the rail member 14.

[0075] Because many of the structural features of each hydroformedmember are formed during a hydroforming operation that creates the same,a preferred method of hydroforming the tubular hydroformed components ofthe space frame 10 will be considered. A preferred hydroformingoperation for forming the hydroformed support member 10 can beunderstood from FIG. 26. An example of a hydroforming operation will begiven using member 190. Each hydroformed member, such as hydroformedU-shaped member 190, may be formed from a tubular blank 302. The blank302 is constructed of a suitable metallic material and has a closedtransverse cross section and open tubular ends. Preferably, the blank302 is constructed of a suitable grade of steel. Each blank 302 may beformed by any suitable method. For example, a continuous strip ofmetallic material may be shaped by roll forming and seam welding to havea closed transverse cross section. Alternatively, a continuous length ofmetallic tubing may be formed by extrusion. The continuous tubularstructure may then be cut to the length required to form a U-shapedmember 190.

[0076] The blank 302 is preferably bent into a “U” shape prior to beingplaced in a hydroforming die assembly. Each leg portion of the member302 preferably forms relatively sharp angle with the central crossportion thereof. Because the angle in the U-shaped member 190 isrelatively “sharp” (that is, at an angle greater than 30°), these anglesrequire relatively sharp bends in the blank 302. Preferably the presentinvention bends the blank 302 according the teachings of U.S. Pat. No.5,953,945 entitled METHOD AND APPARATUS FOR WRINKLE-FREE HYDROFORMING OFANGLED TUBULAR PARTS, which is hereby incorporated herein by referencein its entirety. The teachings of the '945 patent reference can be usedto avoid wrinkle formation during the bending operation, particularly onthe concave portion of each bend in a hydroformed part. A blank 302 maybe bent in a computer numeric controlled (“CNC”) bending machine priorto being placed in the die assembly or, alternatively, may be bent bystretch bending to achieve the “U” shape. The U-shaped blank 302includes an essentially straight, longitudinally extending centralportion and a pair of legs extending from opposite ends of the centralportion. The juncture or “elbow” formed between the central portion andeach leg defines a concave exterior surface portion on one side thereofand a convex exterior surface portion on an opposite side thereof. Asuitable lubricant may be applied to the exterior of the blank 302 priorto placing it in the die assembly.

[0077] With reference again to FIG. 26, the U-shaped tubular blank 302is then placed between the die halves 304, 306 of the die assembly 308and the assembly is closed. The tubular blank 302 is preferably immersedin a fluid bath so that it is filled with hydroforming fluid. Ahydroforming ram assembly 310, 312 is engaged with each end of thetubular blank 302 such that a ram member 314, 316 of each assembly 310,312 seals a respective end of a tubular blank 302. The ram members 314,316 include hydraulic intensifiers which can intensify the hydroformingfluid, thereby increasing the fluid pressure of the fluid within theblank 302 to outwardly deform tubular metallic wall, generallydesignated 318, of the tubular blank 302 into conformity with the diesurfaces 320 of the die cavity (as disclosed in the '945 patentreference) to thereby form a hydroformed member having an exteriorsurface that is fixed into a predetermined regular or irregular(depending on the shape of the die cavity) configuration.

[0078] The tubular blank 302 may have, for example, an essentially equaldiameter, essentially circular cross section prior to outward expansionduring the hydroforming process. The hydroforming process may becomputer controlled. The flow of the hydroforming fluid may becontrolled to control, in turn, the manner in which the metallicmaterial of the blank 302 “flows” (in a radial direction) or expandsduring the hydroforming process. Preferably, the ram members 314, 316push axially inwardly on opposite ends of the blank 302 to create metalflow within the blank 302 during outward expansion. The fluid pressureand the axial pressure are independently controllable. Preferably, theends of the tubular blank 302 are pushed axially inwardly during thehydroforming operation to maintain the wall thickness of the fullyformed hydroformed member 190 within a predetermined range of the wallthickness of the initial tubular blank 302. Because each juncture isdefines an area in which the straight tubular blank is bent at arelatively sharp angle, the exterior surface of the blank 302 has aconcave surface portion and a convex surface portion on generallyopposite sides of the blank 302. Preferably each ram member 314, 316applies a force to the associated end of the blank 302 so as to createlongitudinal flow of metallic material within the blank 302 to maintaina wall thickness of the blank within a predetermined range andpreferably the ram members apply a greater amount of force to a portionof the blank which is longitudinally aligned with the convex surfaceportion of the tubular blank in comparison with the amount of forceapplied to a portion of the blank which is longitudinally aligned withthe concave surface portion of the blank so as to create a greateramount of flow of metal material toward portions of the blank 302 thatare adjacent the convex surface portion in comparison with portions ofthe blank adjacent the concave surface portion. This inhibits wrinkleformation in portions of the blank adjacent the concave surface portionas discussed in detail in the aforesaid '945 patent reference.Preferably the ram members 314, 316 cooperate to replenish or maintainthe wall thickness of the outwardly expanding wall portions of the blank302 so that the wall thickness of the resulting hydroformed member iswithin about ±10% of the original wall thickness of the blank 302 (i.e.,to compensate for wall thinning during diametric outward expansion ofthe tube).

[0079] The tubular blank 302 expands into conformity with the surfacesdefining the hydroforming die cavity so as to irregularly outwardlyexpand the metallic wall of the blank 302 into conformity with thesurfaces of the die assembly to provide the metallic wall with a shapecorresponding to the U-shaped member 190. The shape of each die cavityused to form the support member 10 thus corresponds to the shape of theU-shaped member 190.

[0080] If holes are to be formed in the U-shaped member 190, the holesmay be formed while the member 190 is in the die assembly during thehydroforming operation or may be formed after the hydroformed member 190is removed from the die assembly along with any other required furtherprocessing of the member 190. More particularly, holes may be formedduring the hydroforming process in what is known as a hydropiercingoperation. A hydropiercing operation is disclosed in U.S. Pat. No.5,460,026, which is hereby incorporated by reference in its entiretyinto the present application. Alternatively, holes or notches of varioussizes and shapes may be cut (preferably using a laser) in the member 190after the hydroforming operation is completed.

[0081] It can be appreciated that, as a result of the expansion of theblank 302 during the hydroforming operation, the transverse crosssection of the U-shaped member 190 varies along its length so that thecentral portion of the member 190 may have a relatively small, somewhatrectangular cross-section and each leg portion may have a relativelylarger, essentially rectangular cross-section. It is also contemplatedto hydroform the various portions of the U-shaped member 190 to is haveother cross sectional configurations (including other sizes and shapes).It can thus be understood that altering the cross-sectionalconfiguration of this tubular hydroformed member 190 can be accomplishedwithout departing from the principles of the present invention.

[0082] The space frame 10 is referred to as a “hybrid” space framebecause it incorporates non-hydroformed members, that is, members thatcan be formed utilizing methods other than hydroforming such as, forexample, by sheet metal stamping, (i.e., the forward-most pillarassemblies 94, 96 which comprise the A pillars and the pillar supportassemblies 98, 99 for the C pillars) into a predominantly tubularhydroformed frame assembly (comprised of the lower frame assembly 12 andthe upper frame assembly 170). This hybrid frame construction allowsautomobile manufacturers to implement the space frame concept invehicles having limited space between the interior and the exterior ofthe motor vehicle. The integration of non-hydroformed components in anotherwise hydroformed frame enables the vehicle manufacturer to providea weight efficient vehicle space frame in a package that fits within thespace constraints inherent in a certain vehicle designs.

[0083] More specifically, it can be appreciated from, for example, FIGS.1-4 that the front and rear wheels (not shown in the figures butgenerally disposed within wheel wells 52 and 56, respectively, of theassembled vehicle) are very near to the passenger compartment area 60 inthe longitudinal vehicle direction. For example, the rearward-mostextent of the front wheel is longitudinally spaced only a fewmillimeters (perhaps on the order of 30-40 mm) from the dash panel 104(which generally defines the forward-most extent of the passengercompartment area 60. Similarly, the forward-most extent of the rearwheel is longitudinally spaced very close to the rearward-most extent ofthe passenger compartment area 60. This short wheelbase (i.e., thelongitudinal length between the front and rear wheels) relative to thelongitudinal length of the passenger compartment area 60 and theconsequent relatively close longitudinal spacing of the front and rearwheels to the passenger compartment area 60 require the formation of twoapproximately 90 degree transitions to define the front and rear wheelwells 52, 56. The tubular hydroformed rail members 14, 16 cannot beeasily shaped to curve or “transition” from the rocker panel formingportions (sections 36 and 38, for example) thereof inwardly atapproximately a 90 degree angle (i.e., laterally) and thenlongitudinally at approximately a 90 degree angle to forming the wheelwells 52, 56. It can be appreciated from FIG. 1, for example, that thetransition angle between the longitudinally extending section 36 of thecentral portion 20 of the rail member 14 and the angled section 34thereof is not sharp enough to define the full extent of the rockerpanel of the vehicle space frame and the rearward portion of the frontwheel well 52. The non-hydroformed pillar support structure 44 providesthe forward most end of the rocker panel and provides a relatively sharp(approximately 90 degree) transition angle between the rocker panelportion 54 of the space frame 10 and the rear portion of the front wheelwell 52. Thus, this hybrid design allows the vehicle manufacturer toincorporate a pair of tubular hydroformed lower side rail members 14, 16that extend the length of the vehicle while still meeting the packagingrequirements for manufacturing a compact vehicle.

[0084] The benefits of this hybrid construction can be appreciated fromFIG. 5, which shows the hydroformed portion of the space frame 10 inisolation with the non-hydroformed portions removed and not shown. Itcan be appreciated from this view that the A pillars (not shown in FIG.5 but positioned generally below and in line with the downwardlyextending free ends of the roof rails 106) and the C pillars are spacedlaterally outwardly from one another to maximize the width of thepassenger compartment area 60. Because the hydroformed lower side railmembers 14, 16 transition angularly at the front and rear portionsthereof to help define the front and rear wheel wells 52, 56, the freeends of the roof rails 106 and the free ends of the C pillars are spacedoutwardly from the portions of the hydroformed rail members 14, 16below. The non-hydroformed or stamped forwardmost pillar assembly 94, 96and the pillar support assemblies 98, 99 provide the A pillars andsupport the C pillars, respectively, while still fitting within thecompact vehicle design package.

[0085] The rail sections 34, 36, 38, 40, the non-hydroformed or stampedpillar support structures 44, 46, the inner rails 76, 78 and theconnecting structures 66, 68, 70, 86 generally comprise a “torque box”which includes a section of the lower frame assembly 12 under thepassenger compartment area 60 that reacts to crash loads. By making theA pillars and the box-like pillar support structures 44, 46 intonon-hydroformed or stamped structures, the space frame 10 is able toreact to crash loads both on the outer hydroformed longitudinallyextending side rail members 14, 16 and on the inner stamped longitudinalrails 76, 78. Because the connecting members 66 and 68 are of tubularhydroformed construction and thus have a relatively high degree ofstrength to, for example, support loads and to resist information duringimpact, these cross members 66, 68 are architectural in the sense thatthey support the seats load and improve the torsional properties of thevehicle by making the vehicle torsionally rigid.

[0086] The non-hydroformed construction of the A pillar assemblies 94,96 provides improved incorporation of various frame components over acompletely hydroformed design. For example, because each A pillar can beof non-hydroformed construction, such as stamped construction, it can bebetter integrated into the surrounding sheet metal structures includingthe dash panel, a shock tower 299 (see, for example, FIG. 3) the upperand lower plenum structures and so on. The shock tower 299 may beprovided for housing a strut assembly for the front suspension, such asa MacPherson strut assembly.

[0087] It should be understood that in the description of theillustrated embodiment reference to welding to couple elements togetheris only one possible manner of coupling the elements together and thatother fastening mechanisms or fasteners can be used instead of ortogether with welding. Also, it should be understood that thenon-hydroformed members discussed herein can be formed of anynon-hydroforming process including stamping and other types ofprocesses. The references to “stamping” and to “stamped” sheet metalconstruction is made since it is a preferred method of manufacturing thenon-hydroformed members in the illustrated embodiment, however, othertypes of non-hydroforming processes can be employed in the illustratedembodiment.

[0088] It can be understood that the embodiment of the vehicle spaceframe shown and described herein is an example only and is not intendedto limit the scope of intention. For example, it is contemplated, toprovide a hybrid space frame for other size vehicles and other types ofvehicles including sports utility vehicles, vans and trucks of alltypes. It is also contemplated to vary the construction of the spaceframe. For example, the example embodiment of the space frame 10 showsthe A pillar being provided by a forward pillar assembly on each sidethereof. It is not intended to limit the scope of the invention to thisconstruction. For example, it is contemplated to form an upper portionof the A pillar or, alternatively, the entire A pillar using a tubularhydroformed member. Each upper longitudinal member may be formed toinclude a forward pillar-forming portion that extends integrallydownwardly from the rail-form portion thereof. The forwardpillar-forming portion of each upper longitudinal member may extenddownwardly to provide pillar structure that forms the entire A pillaror, alternatively, the forward pillar-forming portion may extenddownwardly to form only the upper portion of a pillar structure andthereby form only an upper portion of the associated A pillar. When theforward pillar-forming portion of the upper longitudinal member formsthe entire A pillar, the lower end of the forward pillar-forming portionmay be secured to the associated lower side rail member utilizing astamped sheet metal assembly such as, for example, pillar supportstructure 44. When the forward pillar-forming portion of the upperlongitudinal member forms only an upper portion of the associated Apillar, the lower portion of the A pillar may be provided by an assemblyof stamped sheet metal components. For example, a forward pillarassembly similar to forward pillar assembly 94 except vertically shortercould be constructed to provide a lower portion of the associated Apillar and to couple with the forward pillar-forming portion of theassociated upper longitudinal member. In this instance, then, a lowerportion of each A pillar is of stamped sheet metal construction and theupper portion of each A pillar is of tubular hydroformed construction.

[0089] It can be understood that, while illustrated embodiments of theinvention have been disclosed and described with reference with alimited number of embodiments, it will be apparent that variations andmodifications may be made thereto without departing from the spirit andscope of the invention. Therefore, the following claims are intended tocover such modifications, variations, and equivalents thereof inaccordance with the principles and advantages noted herein.

What is claimed is:
 1. A space frame for a motor vehicle, comprising: apair of hydroformed longitudinally extending lower side rail members; apair of hydroformed upper longitudinal members, each of said pair ofsaid upper longitudinal members including a rear, pillar-forming portionand a rail-forming portion, each of said pillar-forming portions beingcoupled to an end of a respective one of said lower side rail membersand extending upwardly from said respective lower side rail member todefine a rearward-most pillar of said motor vehicle, each of saidrail-forming portions extending forwardly from said pillar-formingportion to define a roof support rail of said motor vehicle; a pair offorward-most pillar assemblies, each of said pair of forward-most pillarassemblies being coupled a respective one of said pair of lower siderail members and extending upwardly from said respective lower side railmember and being coupling with a respective one of said upperlongitudinal members, and each of said forward-most pillar assembliesbeing formed from stamped sheet metal; and a laterally extendingconnecting structure mounted between said pair of lower side railmembers, said connecting structure being constructed and arranged tohold said pair of lower side rail members in laterally spaced relationto one another.
 2. A space frame as defined in claim 1, wherein eachhydroformed upper longitudinal member further includes a forwardpillar-forming portion extending from a forward end of an associatedroof support rail, the forward pillar forming portion of each said upperlongitudinal member being coupled to an associated forward-most pillarassembly to define a pair of A pillars of said motor vehicle, eachforward-most pillar assembly defining a lower portion of the associatedA pillar and the forward pillar-forming portion of each upperlongitudinal member defining an upper portion of the associated Apillar.
 3. A space frame as defined in claim 1, wherein eachforward-most pillar structure is coupled to a forward end of therail-forming portion of the associated upper longitudinal member, eachof said forward-most pillar assemblies defining an A pillar of saidmotor vehicle.
 4. A space frame as defined in claim 3, wherein a forwardportion of each of said pair of lower side rail members defines a firstportion of a respective front wheel well.
 5. A space frame as defined inclaim 4, wherein a lower portion of each of said forward-most pillarstructures forms a second portion of said respective front wheel well.6. A space frame as defined in claim 3, wherein each of saidforward-most pillar assemblies is connected to an exterior side portionof said respective lower side rail member.
 7. A space frame as definedin claim 6, wherein an intermediate portion of each lower side railmember defines a portion of a rocker panel on a respective side of saidmotor vehicle and wherein the forward portion of each lower side railmember curves inwardly from the respective intermediate portion thereofto define each said front wheel well, each forward most pillar assemblybeing coupled to the intermediate portion of the associated lower siderail member of such that each forward-most pillar assembly defines aforward portion of the associated rocker panel.
 8. A space frame asdefined in claim 7, wherein the A pillar defined by each forward-mostpillar assembly has a closed cross section.
 9. A space frame as definedin claim 1, wherein each of said lower side rail members includes three,individual pieces.
 10. A space frame for a motor vehicle, comprising: apair of hydroformed longitudinally extending lower side rail members; apair of hydroformed upper longitudinal members, each of said pair ofsaid upper longitudinal members including a rear pillar-forming portionand a rail-forming portion, each of said pillar-forming portions beingcoupled to an end of a respective one of said lower side rail membersand extending upwardly from said respective lower side rail member todefine a rearward-most pillar of said motor vehicle, each of saidrail-forming portions extending forwardly from said rear pillar-formingportion to define a roof support rail of said motor vehicle; a pair ofpillar support structures, each pillar support structure being ofstamped sheet metal construction and each said pillar support structurebeing connected to a respective lower side rail member at the locationto support a forward-most pillar structure; a pair of forward-mostpillar structures, each pillar structure being coupled at a lower endthereof to an associated pillar support structure and being coupled atan upper end thereof to an associated upper longitudinal member; and alaterally extending connecting structure mounted between said pair oflower side rail members, said connecting structure being constructed andarranged to hold said pair of lower side rail members in laterallyspaced relation to one another.
 11. A space frame for a motor vehicle asdefined in claim 10, wherein each upper longitudinal member furtherincludes a forward pillar-forming portion, each forward pillar-formingportion extending from a forward end of the rail portion of theassociated upper longitudinal member, each forward pillar-formingportion being connected at a lower end thereof to a respective pillarsupport structure, to provide a forward-most pillar structure on arespective side of said motor vehicle.
 12. A space frame for a motorvehicle as defined in claim 10, wherein each upper longitudinal memberfurther includes a forward pillar-forming portion and each forwardpillar-forming portion extends from the forward end of the rail portionof the associated upper longitudinal member and wherein eachforward-most pillar structure is of stamped sheet metal construction andis coupled to the forward pillar-forming portion of the associated upperlongitudinal member, each forward-most pillar structure and theassociated forward pillar-forming portion of each upper longitudinalmember thereby defining an A pillar on a respective side of said motorvehicle.
 13. A space frame for a motor vehicle as defined in claim 12wherein said forward-most pillar structure has a closed cross section.14. A space frame for a motor vehicle as defined in claim 10, whereineach forward most pillar structure is of stamped sheet metalconstruction, each said forward most pillar structure being connected atan upper end thereof to the rail forming portion of the associated upperlongitudinal member, each forward most pillar structure thereby definingan A pillar on a respective side of said motor vehicle.
 15. A spaceframe for a motor vehicle as defined in claim 14 wherein saidforward-most pillar structure has a closed cross section.
 16. A spaceframe for a motor vehicle, comprising: a pair of hydroformedlongitudinally extending lower side rail members; a pair of hydroformedupper longitudinal members, each of said pair of said upper longitudinalmembers including a rear pillar-forming portion and a rail-formingportion, each of said pillar-forming portions being coupled to an end ofa respective one of said lower side rail members and extending upwardlyfrom said respective lower side rail member to define a rearward-mostpillar of said motor vehicle, each of said rail-forming portionsextending forwardly from said pillar-forming portion to define a roofsupport rail of said motor vehicle; a pair of forward pillar structures,each of said forward pillar structures being coupled with a forwardportion of a respective one of said lower side rail members andextending upwardly therefrom to form a forward-most pillar of said motorvehicle, an upper end of each forward-most pillar structure beingcoupled to a respective upper longitudinal member; a hydroformedintermediate U-shaped cross-member having a cross portion and a pair ofleg portions, each leg portion extending from a juncture at each end ofsaid cross portion; and a pair of pillar support structures, each ofsaid pair of pillar support structures being formed of stamped sheetmetal material and being connected to a respective intermediate portionof a respective one of said lower side rail members, each of said legportions of said intermediate cross member being coupled to a respectiveone of said pair of pillar support structures and extending upwardlytherefrom to form a pair of intermediate pillars of said motor vehicle.17. A space frame as defined in claim 16, wherein a rearward portion ofeach lower side rail member curves inwardly to define a rear wheel well,and wherein each of said pillar support structures is located at one ofsaid rear wheel wells.
 18. A space frame as defined in claim 16, whereineach of said forward-most pillars has a lower end connected to saidrespective lower side rail member and extends upwardly to form said Apillar and forms a portion of a respective front wheel well togetherwith said respective lower side rail member.
 19. A space frame asdefined in claim 16, wherein each of said pair of lower side railmembers is of three piece construction.
 20. A space frame as defined inclaim 16, wherein each of said pair of forward pillar structures isformed of stamped sheet metal material
 21. A space frame as defined inclaim 16, further comprising: a pair of quarter panel extensions formedof stamped sheet metal material, each of said quarter panel extensionsbeing coupled to a respective one of said leg portions of said U-shapedcross-member.
 22. A method of forming a motor vehicle space frame,comprising: forming each of a pair of hydroformed upper longitudinalmembers in a respective hydroforming procedure, each upper longitudinalmember including a pillar forming portion and a rail forming portion;forming each of a pair lower side rail members in respectivehydroforming procedures; stamping metal material to form a plurality ofcomponents constructed and arranged to be assembled into a pair offorward-most pillar assemblies; providing an elongated connectingstructure; and assembling said components, said hydroformed members andsaid connecting structure such that (a) the pillar-forming portion ofeach upper longitudinal member is connected to a respective one of saidlower side rail members to form a rearward most pillar thereon, (b) therail-forming portion of each upper longitudinal member extends forwardlyfrom the associated pillar forming portion thereof to define a roofsupport rail on a respective side of said motor vehicle, (c) eachforward-most pillar assembly is connected between a respective one ofsaid lower side rail members and an associated upper longitudinal memberand (d) said connecting structure is connected between said pair oflower side rail members to hold said lower side rail members inlaterally spaced relation to one another.
 23. A method for forming amotor vehicle space frame as defined in claim 22, wherein each saidhydroformed upper longitudinal member includes a forward pillar-formingportion extending from a forward and of the rail-forming portion thereofand wherein each forward-most pillar assembly is connected to theforward pillar-forming portion of the associated upper longitudinalmember, each forward-most pillar assembly and the associated forwardpillar-forming portion defining an A pillar on a respective side of saidmotor vehicle.
 24. A method for forming a motor vehicle space frame asdefined in claim 22, wherein each forward-most pillar assembly isconnected to the rail-forming portion of the associated upperlongitudinal member, each forward-most pillar assembly defining an Apillar on a respective side of said motor vehicle.
 25. A method forforming a motor vehicle space frame as defined in claim 22, whereinforming each upper longitudinal member includes providing an angularlyshaped blank having a metallic wall, placing the blank in a die assemblyhaving die surfaces defining a die cavity, providing pressurized fluidinto an interior of the blank to expand said wall into conformity withsaid die surfaces and wherein forming each lower side rail memberincludes (a) providing a plurality of blanks each having a metallicwall, (b) placing each said blank in a respective die assembly, each dieassembly having die surfaces defining a die cavity, (c) providingpressurized fluid into an interior of each said blank to expand saidwall into conformity with said die surfaces, each blank of saidplurality of blanks of each lower side rail member forming a hydroformedportion of the respective lower side rail member and (d) joining theplurality of hydroformed portions of said lower side rail member.
 26. Amethod of forming a motor vehicle space frame, comprising: forming ahydroformed cross member in a hydroforming procedure, said cross memberincluding a cross portion and a pair of pillar forming leg portions,each leg portion extending from a juncture at a respective end of thecross portion; forming each of a pair of hydroformed upper longitudinalmembers in a respective hydroforming procedure, each upper longitudinalmember including a pillar forming portion and a rail forming portion;forming each of a pair lower side rail members in a respectivehydroforming procedure, forward and rearward portions of said lower siderail member defining forward and rearward wheel wells, respectively;stamping metal material to form a plurality of components constructedand arranged to be assembled into a pair of forward-most pillarassemblies; stamping metal material to form a plurality of componentsconstructed and arranged to be assembled into a pair of pillar supportassemblies; providing an elongated connecting structure; and assemblingsaid components, said hydroformed members and said connecting structuresuch that (a) the pillar-forming portion of each upper longitudinalmember is connected to a respective one of said lower side rail membersto form a rearward most pillar thereon, (b) the rail-forming portion ofeach upper longitudinal member extends forwardly from the associatedpillar forming portion thereof to define a roof support rail on arespective side of said motor vehicle, (c) each forward-most pillarassembly is connected between a respective one of said lower side railmembers and an associated upper longitudinal member, (d) each pillarsupport assembly is connected to a respective lower side rail memberadjacent the rear wheel well thereof, (e) each juncture of said crossmember is connected to an intermediate portion of the roof rail portionof an associated upper longitudinal member and each leg portion of saidintermediate cross member is coupled to a respective one of said pair ofpillar support assemblies and extends upwardly therefrom to form anintermediate pillar of said motor vehicle and (f) said connectingstructure is connected between said pair of lower side rail members tohold said lower side rail members in laterally spaced relation to oneanother.
 27. A method of forming a motor vehicle space frame as definedin claim 26, wherein forming said cross member includes (a) providing anangularly shaped blank having a metallic wall, (b) placing the blank ina die assembly having die surfaces defining a die cavity and (c)providing pressurized fluid into an interior of the blank to expand saidwall into conformity with said die surfaces, wherein forming each saidupper longitudinal member includes (a) providing an angularly shapedblank having a metallic wall, (b) placing the blank in a die assemblyhaving die surfaces defining a die cavity and (c) providing pressurizedfluid into an interior of the blank to expand said wall into conformitywith said die surfaces and wherein forming each lower side rail memberincludes (a) providing a plurality of blanks each having a metallicwall, (b) placing each said blank in a respective die assembly, each dieassembly having die surfaces defining a die cavity, (c) providingpressurized fluid into an interior of each said blank to expand saidwall into conformity with said die surfaces, each blank of saidplurality of blanks of each lower side rail member forming a hydroformedportion of the respective lower side rail member and (d) joining theplurality of hydroformed portions of said lower side rail member.